Principles Related to Practical Chemistry — JEE Main PYQs

Identify the colour of compound 'X' in the sequence of the reaction.

[Figure: 2 phenol + phthalic anhydride $\xrightarrow{\text{conc. } \mathrm{H_2SO_4}}$ phenolphthalein $\xrightarrow{\mathrm{NaOH}}$ pink quinonoid form $\xrightarrow{\text{Excess NaOH}}$ X (carbinol/tri-anionic form with $-\mathrm{OH}$, two $-\mathrm{O^-}$ groups and $-\mathrm{COO^-}$)]

Among $\mathrm{Fe^{3+}}$, $\mathrm{Pb^{2+}}$, $\mathrm{Cu^{2+}}$ and $\mathrm{Mn^{2+}}$, identify the one that gets precipitated out while passing $\mathrm{H_2S}$ in presence of $\mathrm{NH_4OH}$ as group reagent. The highest possible oxidation state of the corresponding metal is

Match the LIST-I with LIST-II

List-I (Compound)	List-II (Test)
A. [structure: cyclohexanol]	I. Hinsberg's reagent test
B. [structure: cyclohexanamine (cyclohexyl-$\mathrm{NH_2}$)]	II. Phthalein dye test
C. [structure: cyclohexanecarbaldehyde (cyclohexyl-CHO)]	III. Lucas test
D. [structure: phenol]	IV. Tollen's test

Choose the correct answer from the options given below:

Given below are two statements:

Statement I: Sodium dichromate and potassium dichromate are classified as primary standards in titrimetric analysis.

Statement II: Phenolphthalein is a weak base, therefore it dissociates in acidic medium.

In the light of the above statements, choose the correct answer from the options given below

A paper dipped in a dil. $\mathrm{H_2SO_4}$ solution of 'X' upon treatment with $\mathrm{SO_2}$ gas turns into green. The compound 'X' is :

Choose the correct tests with respective observations.

(A) $\mathrm{CuSO_4}$ (acidified with acetic acid) $+ \mathrm{K_4[Fe(CN)_6]} \rightarrow$ Chocolate brown precipitate. (B) $\mathrm{FeCl_3} + \mathrm{K_4[Fe(CN)_6]} \rightarrow$ Prussian blue precipitate. (C) $\mathrm{ZnCl_2} + \mathrm{K_4[Fe(CN)_6]}$, neutralised with $\mathrm{NH_4OH} \rightarrow$ White or bluish white precipitate. (D) $\mathrm{MgCl_2} + \mathrm{K_4[Fe(CN)_6]} \rightarrow$ Blue precipitate. (E) $\mathrm{BaCl_2} + \mathrm{K_4[Fe(CN)_6]}$, neutralised with NaOH $\rightarrow$ White precipitate.

Choose the correct answer from the options given below :

Formation of $\mathrm{Na_4[Fe(CN)_5NOS]}$, a purple coloured complex formed by addition of sodium nitroprusside in sodium carbonate extract of salt indicates the presence of :

Compounds that should not be used as primary standards in titrimetric analysis are :

A. $\mathrm{Na_2Cr_2O_7}$ B. Oxalic acid C. NaOH D. $\mathrm{FeSO_4 \cdot 6H_2O}$ E. Sodium tetraborate

Choose the most appropriate answer from the options given below:

When a salt is treated with sodium hydroxide solution it gives gas X. On passing gas X through reagent Y a brown coloured precipitate is formed. X and Y respectively, are

Match the LIST-I with LIST-II

	LIST-I (Reagent)		LIST-II (Functional Group detected)
A.	Sodium bicarbonate solution	I.	double bond/ unsaturation
B.	Neutral ferric chloride	II.	carboxylic acid
C.	ceric ammonium nitrate	III.	phenolic - OH
D.	alkaline $\mathrm{KMnO_4}$	IV.	alcoholic - OH

Choose the correct answer from the options given below:

Identify A, B and C in the given below reaction sequence

$$[A] \xrightarrow{\text{HNO}_3} \mathrm{Pb(NO_3)_2} \xrightarrow{\text{H}_2\text{SO}_4} [B] \xrightarrow[\substack{(2)\ \text{Acetic acid}\\ (3)\ \mathrm{K_2CrO_4}}]{(1)\ \text{Ammonium acetate}} [C]\ (\text{Yellow ppt})$$

Among the following cations, the number of cations which will give characteristic precipitate in their identification tests with $\mathrm{K_4[Fe(CN)_6]}$ is ______. $\mathrm{Cu^{2+},\ Fe^{3+},\ Ba^{2+},\ Ca^{2+},\ NH_4^{+},\ Mg^{2+},\ Zn^{2+}}$

Find the compound 'A' from the following reaction sequences.

\mathrm{A} \xrightarrow{\text{aqua-regia}} \mathrm{B} \xrightarrow[\text{(2) AcOH}]{\text{(1) KNO_2 | NH_4OH}} \text{yellow ppt}

Given below are two statements:

Statement I: In the oxalic acid vs $\mathrm{KMnO_4}$ (in the presence of dil $\mathrm{H_2SO_4}$) titration the solution needs to be heated initially to 60°C, but no heating is required in Ferrous ammonium sulphate (FAS) vs $\mathrm{KMnO_4}$ titration (in the presence of dil $\mathrm{H_2SO_4}$)

Statement II: In oxalic acid vs $\mathrm{KMnO_4}$ titration, the initial formation of $\mathrm{MnSO_4}$ takes place at high temperature, which then acts as catalyst for further reaction. In the case of FAS vs $\mathrm{KMnO_4}$, heating oxidizes $\mathrm{Fe^{2+}}$ into $\mathrm{Fe^{3+}}$ by oxygen of air and error may be introduced in the experiment.

In the light of the above statements, choose the correct answer from the options given below

Identify the inorganic sulphides that are yellow in colour :

(A) $\mathrm{(NH_4)_2S}$ (B) $\mathrm{PbS}$ (C) $\mathrm{CuS}$ (D) $\mathrm{As_2S_3}$ (E) $\mathrm{As_2S_5}$

Choose the correct answer from the options given below :

In the precipitation of the iron group (III) in qualitative analysis, ammonium chloride is added before adding ammonium hydroxide to :

When $\mathrm{MnO_2}$ and $\mathrm{H_2SO_4}$ is added to a salt (A), the greenish yellow gas liberated as salt (A) is :

[Figure: flame diagram with two marked zones — A (upper, outer zone) and B (lower, inner zone)]

In a borax bead test under hot condition, a metal salt (one from the given) is heated at point B of the flame, resulted in green colour salt bead. The spin-only magnetic moment value of the salt is ________ BM (Nearest integer)

[Given atomic number of Cu = 29, Ni = 28, Mn = 25, Fe = 26]

While preparing crystals of Mohr's salt, dil $\mathrm{H_2SO_4}$ is added to a mixture of ferrous sulphate and ammonium sulphate, before dissolving this mixture in water, dil $\mathrm{H_2SO_4}$ is added here to :

Match List I with List II

LIST I (Precipitating reagent and conditions)	LIST II (Cation)
A. $\mathrm{NH_4Cl + NH_4OH}$	I. $\mathrm{Mn^{2+}}$
B. $\mathrm{NH_4OH + Na_2CO_3}$	II. $\mathrm{Pb^{2+}}$
C. $\mathrm{NH_4OH + NH_4Cl + H_2S}$ gas	III. $\mathrm{Al^{3+}}$
D. dilute HCl	IV. $\mathrm{Sr^{2+}}$

Choose the correct answer from the options given below:

During the detection of acidic radical present in a salt, a student gets a pale yellow precipitate soluble with difficulty in $\mathrm{NH_4OH}$ solution when sodium carbonate extract was first acidified with dil. $\mathrm{HNO_3}$ and then $\mathrm{AgNO_3}$ solution was added. This indicates presence of :

Consider the following reactions

$$\mathrm{NiS + HNO_3 + HCl \to A + NO + S + H_2O}$$

$$\mathrm{A + NH_4OH + \underset{\underset{\displaystyle \mathrm{H_3C{-}C{=}N{-}OH}}{|}}{H_3C{-}C{=}N{-}OH} \to B + NH_4Cl + H_2O}$$

The number of protons that do not involve in hydrogen bonding in the product B is ________.

Match List I with List II

	LIST I (Name of the test)		LIST II (Reaction sequence involved) [M is metal]
A.	Borax bead test	I.	$\mathrm{MCO_3 \rightarrow MO \xrightarrow{Co(NO_3)_2,\ +\Delta} CoO \cdot MO}$
B.	Charcoal cavity test	II.	$\mathrm{MCO_3 \rightarrow MCl_2 \rightarrow M^{2+}}$
C.	Cobalt nitrate test	III.	$\mathrm{MSO_4 \xrightarrow[\Delta]{Na_2B_4O_7} M(BO_2)_2 \rightarrow MBO_2 \rightarrow M}$
D.	Flame test	IV.	$\mathrm{MSO_4 \xrightarrow[\Delta]{Na_2CO_3} MCO_3 \rightarrow MO \rightarrow M}$

Choose the correct answer from the options given below:

Match List I with List II

	LIST I (Compound)		LIST II (Colour)
A.	$\mathrm{Fe_4[Fe(CN)_6]_3 \cdot xH_2O}$	I.	Violet
B.	$\mathrm{[Fe(CN)_5NOS]^{4-}}$	II.	Blood Red
C.	$\mathrm{[Fe(SCN)]^{2+}}$	III.	Prussian Blue
D.	$\mathrm{(NH_4)_3PO_4 \cdot 12MoO_3}$	IV.	Yellow

Choose the correct answer from the options given below:

Match List - I with List - II.

List - I (Test)	List - II (Identification)
(A) Bayer's test	(I) Phenol
(B) Ceric ammonium nitrate test	(II) Aldehyde
(C) Phthalein dye test	(III) Alcoholic-OH group
(D) Schiff's test	(IV) Unsaturation

Choose the correct answer from the options given below :

Identify the incorrect statements regarding primary standard of titrimetric analysis. (A) It should be purely available in dry form. (B) It should not undergo chemical change in air. (C) It should be hygroscopic and should react with another chemical instantaneously and stoichiometrically. (D) It should be readily soluble in water. (E) $\mathrm{KMnO_4}$ & NaOH can be used as primary standard. Choose the correct answer from the options given below :

Match List I with List II

	LIST I (Test)		LIST II (Observation)
A.	$\mathrm{Br_2}$ water test	I.	Yellow orange or orange red precipitate formed
B.	Ceric ammonium nitrate test	II.	Reddish orange colour disappears
C.	Ferric chloride test	III.	Red colour appears
D.	2, 4 - DNP test	IV.	Blue, Green, Violet or Red colour appear

Choose the correct answer from the options given below:

Consider the following test for a group-IV cation.

$\mathrm{M^{2+} + H_2S \rightarrow A}$ (Black precipitate) + byproduct

A + aqua regia $\rightarrow \mathrm{B + NOCl + S + H_2O}$

$\mathrm{B + KNO_2 + CH_3COOH \rightarrow C}$ + byproduct

The spin-only magnetic moment value of the metal complex C is ________ BM (Nearest integer)

Given below are two statements :

Statement (I) : Potassium hydrogen phthalate is a primary standard for standardisation of sodium hydroxide solution.

Statement (II) : In this titration phenolphthalein can be used as indicator.

In the light of the above statements, choose the most appropriate answer from the options given below :

The number of white coloured salts, among the following is ________.

(a) $\mathrm{SrSO_4}$ (b) $\mathrm{Mg(NH_4)PO_4}$ (c) $\mathrm{BaCrO_4}$ (d) $\mathrm{Mn(OH)_2}$

(e) $\mathrm{PbSO_4}$ (f) $\mathrm{PbCrO_4}$ (g) $\mathrm{AgBr}$ (h) $\mathrm{PbI_2}$

(i) $\mathrm{CaC_2O_4}$ (j) $\mathrm{[Fe(OH)_2(CH_3COO)]}$

Given below are two statements :

Statement (I) : Dimethyl glyoxime forms a six-membered covalent chelate when treated with $\mathrm{NiCl_2}$ solution in presence of $\mathrm{NH_4OH}$.

Statement (II) : Prussian blue precipitate contains iron both in (+2) and (+3) oxidation states.

In the light of the above statements, choose the most appropriate answer from the options given below :

NaCl reacts with conc. $\mathrm{H_2SO_4}$ and $\mathrm{K_2Cr_2O_7}$ to give reddish fumes (B), which react with NaOH to give yellow solution (C). (B) and (C) respectively are :

In chromyl chloride test for confirmation of $\mathrm{Cl^-}$ ion, a yellow solution is obtained. Acidification of the solution and addition of amyl alcohol and 10% $\mathrm{H_2O_2}$ turns organic layer blue indicating formation of chromium pentoxide. The oxidation state of chromium in that is

Given below are two statements :

Statement (I) : The gas liberated on warming a salt with dil $\mathrm{H_2SO_4}$, turns a piece of paper dipped in lead acetate into black, it is a confirmatory test for sulphide ion.

Statement (II) : In statement-I the colour of paper turns black because of formation of lead sulphite.

In the light of the above statements, choose the most appropriate answer from the options given below :

Number of metal ions characterized by flame test among the following is ______.

$$\mathrm{Sr^{2+},\ Ba^{2+},\ Ca^{2+},\ Cu^{2+},\ Zn^{2+},\ Co^{2+},\ Fe^{2+}}$$

The compound that is white in color is

Molar mass of the salt from $\mathrm{NaBr}$, $\mathrm{NaNO_3}$, $\mathrm{KI}$ and $\mathrm{CaF_2}$ which does not evolve coloured vapours on heating with concentrated $\mathrm{H_2SO_4}$ is ________ $\mathrm{g\,mol^{-1}}$.

(Molar mass in $\mathrm{g\,mol^{-1}}$ : Na : 23, N : 14, K : 39, O : 16, Br : 80, I : 127, F : 19, Ca : 40)